Pick out a cute t-shirt. The size you need depends on the size of the kid you're sewing for. I've used a Youth size 14/16 and a Women's Medium for my size 2T daughter. Obviously for a bigger kid, you'll need a bigger shirt.

Carefully cut off the sleeves at the seams.

-= BODICE =-

Determine whether or not you're going to need to adjust the shoulder seams. On the one I made from a Youth size 14/16, I didn't need to adjust the shoulder seams because the neck size was almost identical to the one on my daughter's shirt. (The width of the binding doesn't matter, just the inner edge).

Lucky for you, the shirt I used for this tutorial was quite a bit wider at the neck, so you get to see how to adjust the shoulder seams.

If you're not sure, just try it on your kid and see how the neck fits! Definitely too big, see?

Line up the inner neck edge of the kids shirt with the inner neck edge of the big t-shirt. The idea is to get the neck to come out the same width. I'm not doing so well explaining this part, hopefully the pictures will help!

Once your shirts are in position, you'll need to know how long you want the bodice of the dress to be. I did mine at 7 inches, plus a half inch for seaming and mistakes (just in case). You could do a dropped waist or a higher empire line, whatever suits your fancy!

Here's where it's nice to use a striped shirt...you can just follow a stripe across, but beware! Store bought clothes are sometimes pretty crooked! I cut the front and back pieces separately so nothing goes awry.

Cut straight up along one side of the kid's shirt...remember to leave room for a seam!

Fold in half and cut the other side.

Since my shoulders only needed to be moved down about a half an inch, I decided not to cut it first. I just turned it inside out and serged new seams a half inch down. You may need to cut it off a bit. Just use your kid's t-shirt as a guide...and remember to add seam allowances.

(The pins are just to show you the sewing line...don't pin like this if you use a serger!)

-= SLEEVES =-

Use the sleeves of your kids shirt to determine the new sleeves width.

Cut across following the general shape of the original underarm seam.

Measure sleeve length and make whatever adjustments you need. Six inches would be down to my daughter's elbow, so I cut off about an inch.

Use the first sleeve to make the second sleeve. Easy peasy.

-= ARMHOLE SHAPING =-

Use the curved edge of the sleeve as a guide for the armholes. Err on the side of caution...it's better to cut the hole too small and have to cut it bigger later! The pin is marking the center fold of the sleeve so it can be aligned with the shoulder seam.

Fold the bodice in half and cut the other side to match.

Whew, that was the hard part. After this it's all smooth sailin'!

Pin the sleeves in place and sew. Don't forget to put right sides together! (Check the hems to know which is the inside and which is the outside of the fabric). For the best look, press sleeve seams.

My bodice is 7 1/2 inches, and I want my finished dress to be between 17 and 18 inches, so I measured 11 up from the hem and cut. You may want more or less depending on your kid...and also on the size of your shirt.

Use your favorite method of gathering...I used my longest stitch on my sewing machine. Pin skirt to bodice matching center front, center back, and side seams. Be careful to get right sides together again. It's easy to mess up since both sides of the cloth look the same.